BIO2 Chapt 45 Hormones and Endocrine system Flashcards
What are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
Animal hormones
Where can hormones reach
all parts of the body
Why dont all hormones affect all parts of the body
only target cells have receptors for specific hormone
Chemical signaling by hormones is the function of the
endocrine system
What is a network specialized cells- neurons- that transmit signals along dedicated pathways
nervous system
What is intecellular communication
he process by which signals are transmitted between animal cells.
What are the two criteria used to classify types of intercellular communication?
1- type of secreting cell
2-the route taken by the signal to reach its target
Why are the type of cell and the route important in intercellular communication?
They determine how and where the signal is delivered and how the target respond
Which type of signaling involves hormones traveling through the bloodstream to distant target cells?
endocrine signaling
Which type of signaling involves a cell affecting nearby cells with local signals?
paracrine signaling
Which type of signaling involves a cell sending signals to itself?
Autocrine signaling
Which type of signaling uses neurotransmitters to communicate across synapses?
synaptic signaling
Which type of signaling involves nerve cells releasing hormones into the blood?
neuroendocrine signaling
What are three types of hormones
-polypeptides
-steriods
-amines
Which types of hormones are water soluble
ploypeptides and amines
What type of hormones are lipid soluble
steriod and other largely nonpolar hormones
How are water soluble hormones secreted into the bloodstream
exocytosis
where do water solubles hormones bind to
cell surface receptors
Where do lipid soluble hormones diffuse across
cell membranes
How do lipid soluble hormones travel through the bloodstream
bound to transporter protiens
how do lipid soluble hormones diffuse
go through the membrane of target cells
Where do hormones bind to at the receptors
cytoplasm or nucleus of the target cells
Why can the same hormone have different effects on different target cells? Because target cells may have…
- Different receptors for the hormone
- Different signal transduction pathways
Endocrine cells are often grouped in ductless
organs called
endocrine glands
What are some examples of endocrine glands
thyroid and parathyroid glands, testes, and ovaries
Example of exocrine glands
salivary glands
Exocrine glands have ducts that carry secreted substances onto
body surfaces or into body cavities
What stimulates the release of secretin in the duodenum?
The release of acidic contents from the stomach into the duodenum.
What does secretin cause in the pancreas?
It causes the pancreas to release bicarbonate to raise the pH in the duodenum.
What is the role of secretin in regulating the pH of the duodenum?
Secretin stimulates the pancreas to release bicarbonate, which neutralizes the acidic contents from the stomach.
What does a negative feedback loop do?
A negative feedback loop inhibits a response by reducing the initial stimulus. This helps to prevent excessive activity in a biological pathway, maintaining balance or homeostasis.
With negative feedback looks what happens when body temp rises
mechanisms like sweating are activated to cool the body down, reducing the original stimulus.
What does a positive feedback loop do?
A positive feedback loop amplifies a stimulus, resulting in an even greater response.
What is an example of a positive feedback loop in blood clotting?
When a blood vessel is injured, platelets stick to the site and release chemicals that attract more platelets. This continues until a blood clot forms and seals the wound.
What does insulin do
decreases blood glucose
what does glucagon do
increase blood glucose
What are insulin and glucagon called together, as they have opposing effectd
hormonal antagonists
The pancreas has clusters of endocrine cells
called
pancreatic islets
Pancreatic islets with alpha cells produce
glucagon
Pancreatic islets with beta cells produce
insulin
How does insulin reduce blood glucose levels?
Insulin reduces blood glucose levels by promoting the uptake of glucose into cells.
What does insulin do to glycogen breakdown in the liver?
Insulin slows the breakdown of glycogen in the liver, helping to keep blood sugar levels stable.
What effect does insulin have on fat storage?
Insulin promotes fat storage rather than fat breakdown.
How does glucagon increase blood glucose levels?
Glucagon increases blood glucose levels by stimulating the conversion of glycogen to glucose in the liver.
What does glucagon stimulate in addition to glycogen conversion?
Glucagon stimulates the breakdown of fat and protein into glucose.
In vertebrates what recives info from the nervous system,
hypothalamus
When the hypothalamus recives info from the nervous system what does it do
initiates responses through the endocrine system
What is attached to the hypothalamus, and what is it composed of
pituatary gland, posterior and anterior pituatry
Posterior pituatary does what
stores and secretes hormones that are made in the hypothalamus
Anterior pituatry does what
makes and releases hormones under regulation of the hypothalamus
Where are the two posterior pituitary hormones synthesized?
neurosecretory cells of the hypothalamus
What is the function of antidiuretic hormone (ADH)?
ADH regulates physiology and behavior, particularly water balance in the body.
What does oxytocin regulate?
regulates milk secretion
What controls hormone production in the anterior pituitary?
Hormones released by the hypothalamus, including releasing and inhibiting hormones.
What does prolactin-releasing hormone from the hypothalamus do?
It stimulates the anterior pituitary to secrete prolactin (PRL).
What is the role of prolactin (PRL)?
role in milk production
What happens if thyroid hormone levels drop in the blood?
The hypothalamus secretes thyrotropin-releasing hormone (TRH).
What does thyrotropin-releasing hormone (TRH) cause the anterior pituitary to do?
It causes the anterior pituitary to secrete thyroid-stimulating hormone (TSH).
What is the role of thyroid-stimulating hormone (TSH)?
stimulates thyroid gland to release thyriod hormone
What is hypothyroidism?
Hypothyroidism is a condition where there is too little thyroid function.
What are some symptoms of hypothyroidism?
weight gain, cold intolerance
What is hyperthyroidism?
a condition where there is excessive production of thyroid hormone.
What are some symptoms of hyperthyroidism?
high temperature, sweating, weight loss, irritability, and high blood pressure.
How can malnutrition affect thyroid function?
Malnutrition can alter thyroid function, potentially leading to thyroid-related issues.
What is Graves’ disease?
a form of hyperthyroidism caused by autoimmunity, and it is often characterized by protruding eyes.
What are the two types of thyroid hormones?
Triiodothyronine (T3) and Thyroxine (T4).
How many iodine atoms do T3 and T4 have
T3 has three iodine atoms, T4 has 4 iodine atoms
What can insufficient dietary iodine cause?
It can lead to an enlarged thyroid gland, called a goiter.
Where is growth hormone (GH) secreted from?
anterior pituitary gland
What are the effects of growth hormone (GH)?
GH has both tropic and nontropic effects, promoting growth and having diverse metabolic effects.
What happens if there is an excess of growth hormone (GH)
gigantism
What happens if there is a lack of growth hormone (GH)?
drawrfism
What two hormones regulate calcium homeostasis in the blood of mammals?
Parathyroid hormone (PTH) and calcitonin.
Where is parathyroid hormone (PTH) released from?
The parathyroid glands.
Where is calcitonin released from?
thyroid gland
How does parathyroid hormone (PTH) increase blood calcium levels?
PTH increases blood Ca2+ by releasing Ca2+ from bones and stimulating reabsorption of Ca2+ in the kidneys.
What is the indirect effect of parathyroid hormone (PTH)?
PTH stimulates the kidneys to activate vitamin D, which promotes the intestinal uptake of Ca2+ from food.
How does calcitonin affect blood calcium levels?
Calcitonin decreases blood Ca2+ levels.
What does calcitonin stimulate in the body?
Calcitonin stimulates Ca2+ deposition in bones and secretion of Ca2+ by the kidneys.
Adrenal glands are associated with which organ
kidneys
What does each adrenal gland consist of (2 glands)
the adrenal medulla (inner portion) and Adrenal cortex (outer portion)
What do epinephrine and norepinephrine trigger the release of?
glucose and fatty acids
What does adrenal medulla secrete
epinephrine (adrenaline) and norepinephrine (noradrenaline)
What do epinepherine and norepi increase?
O2 delivery to body cells
Where do Epi and Norepi direct blood to
heart, brain and skeletal muscles
Where do epi and norepi reduce blood flow?
skin, digestive sys and kidneys
What triggers the adrenal cortex to release hormones
endocrine signals
What does the adrenal cortex release in response to stress
A family of steroid hormones called corticosteroids.
What triggers the release of corticosteriods
a hormone cascade starting from the hypothalamus and anterior pituitary
What are two types of corticosteriods produced in humans?
Glucocorticoids and mineralocorticoids
What do glucocorticoids do and give example of one
influence glucose metabolism and the immune system
What do mineralocorticoids do and what is an example
affect salt and water balance, aldosterone
What organs produce the most sex hormones
gonads- testes and ovaries
Three main types of sex hormones
androgens, estrogens and progestins
Do males and females have all three types of sex hormones
yes, but in significantly diff proportions
What do the testes primarly synthesize
androgens, mainly testosterone
What does testosterone do
stimulates develoupment and maintenance of the male reproductive system
What physical effects does test have
increase muscle and bone mass
What is the main estrogen and what is its function?
Estradiol; it maintains the female reproductive system and develops female secondary sex characteristics.
What do progestins like progesterone do in mammals?
prepare and maintain the uterus
What controls the synthesis of sex hormones?
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
What does the pineal gland secrete
melatonin
What is melatonin related to?
Biological rhythms, including reproduction and daily activity levels.
What controls the release of melatonin?
The suprachiasmatic nucleus (SCN), a group of neurons in the hypothalamus.
What do the parathyroid hormones (PTH and Calcitionin) do
regulate blood calcium
Anterior pituatary does what
makes and releases hormones
posterior pituatary does what
stores and secretes hormones
